警告：mysqli_query（）期望参数1为mysqli，null为何？

Question

I am making a website for my high school annual project. The following error occurs in the php file :

Warning: mysqli_query() expects parameter 1 to be mysqli, null given in /host/home1/jbts/html/db/Plot-log.php on line 89

this is php source.

<?php
$link=mysqli_connect("localhost","xxxx","xxxxxxxxx","jbts");
if (!$link)
{ echo "MySQL error : "; echo mysqli_connect_error(); exit(); }
mysqli_set_charset($link,"utf8");
$sql = "select * from Plot-log";
$result = mysqli_query($link, $sql);
?>

and I used in html file like this.

<tr>
    <?  while($row=mysqli_query($con, $sql)){ ?>
        <tr> 
          <td> <?=$row[0]?></td> 
          <td> <?=$row[1]?></td>
          <td>  <?=$row[2]?></td>                                           
</tr>
    <?
    }
    ?>

i need your help... plz :)

Answer 1

To output the data you need to use one of the fetching methods - in this case mysqli_fetch_assoc

<?php
    /* be consistent with the name of the db connection object - $link */

    $link=mysqli_connect("localhost","xxxx","xxxxxxxxx","jbts");
    if( !$link ) exit( "MySQL error : ". mysqli_connect_error() );


    mysqli_set_charset( $link, "utf8" );
    $sql = "select * from `Plot-log`";

    $result = mysqli_query( $link, $sql );

?>

The names below need to be changed to the actual names of the columns in the table.

<?php
    if( $result ){
        while( $rs=mysqli_fetch_assoc( $result ) ){
            echo "
            <tr>
                <td>{$rs['FIELD_NAME_1']}</td>
                <td>{$rs['FIELD_NAME_2']}</td>
                <td>{$rs['FIELD_NAME_3']}</td>
            </tr>";
        }
    }
?>